JP4200891B2 - Fiber Bragg grating device - Google Patents

Description

  The present invention relates to a fiber Bragg grating device used as an encoder and a decoder in optical code division multiplexing transmission.

  In recent years, communication demand has been rapidly increasing due to the spread of the Internet and the like. Correspondingly, high-speed and large-capacity networks using optical fibers and the like are being developed. As one of communication means for constructing such a high-speed and large-capacity optical network, transmission by optical code division multiplexing (OCDM) has been attracting attention.

  In OCDM transmission, multiple-channel optical pulse signals (optical pulse trains are optically modulated and electrical pulse signals are converted into optical pulse signals) are generated in parallel and modulated with different codes for each channel. Transmission on the receiving side using decoding (decoding) means for returning to the original parallel optical pulse signal by decoding with the same code as that used when encoding on the transmitting side. The light constituting the optical pulse signal is sometimes referred to as an optical carrier wave.

  According to the transmission by OCDM, optical pulse signals of many channels can be transmitted simultaneously at the same wavelength. In addition, the transmission method using OCDM is a method in which the same code is used as a key (the code set in the encoder and the decoder may be referred to as a key) on the transmission side and the reception side, so the security in transmission is high. This is one of the features.

  As a means for encoding OCDM, a phase code method OCDM using the phase of light as a code is known. Specifically, a superstructured fiber Bragg grating (SSFBG) is used for an encoder and a decoder. As described above, OCDM transmission uses the same code as a key on the transmission side and the reception side. In the following description, SSFBG may be simply abbreviated as “Fiber Bragg Grating” (FBG) for simplicity.

  In order to help understand the role of the FBG device of the present invention, first, the configuration of a typical OCDM transmission device will be described with reference to the block configuration diagram shown in FIG.

  The OCDM transmission apparatus includes a transmission unit 10 and a reception unit 40, which are connected by a transmission path. The signal transmitted by the OCDM transmission device is an optical pulse signal, and the optical pulse signal is a binary digital electric pulse signal carrying information to be transmitted (this signal is a binary digital of “0” or “1”). It is a pulse signal whose signal value is reflected in the voltage level).

  The transmission unit 10 includes an optical pulse train generator 12, a modulation signal generator 14, an optical modulator 16, a first optical circulator 18, and an encoder 60. The optical pulse train generator 12 generates an optical pulse train 13. The modulation signal generator 14 supplies information to be transmitted to the optical modulator 16 as a binary digital electric pulse signal 15.

  The optical pulse signal 17 to be transmitted output from the optical modulator 16 enters the encoder 60 via the first optical circulator 18. The encoded optical pulse signal is sent again from the encoder 60 to the transmission line 42 as the optical pulse signal 19 through the first optical circulator 18, and propagates through the transmission line 42 and is sent to the receiving unit 40. .

  The receiving unit 40 includes a second optical circulator 22, a decoder 62, an optical coupler 26, a photoelectric converter 28, a wavelength monitor 30, and a wavelength control unit 32. The photoelectric converter 28 converts the optical pulse signal into an electric pulse signal. The wavelength monitor 30 measures the degree of autocorrelation (eye opening size) of the optical pulse signal 29. The wavelength control unit 32 receives the output 31 from the wavelength monitor 30 and supplies a control signal 67 to the temperature controller 68. Upon receiving the control signal 67, the temperature controller 68 controls the current of the thermo module 66 via the cable 69 based on the control signal 67, and controls whether to raise or lower the temperature of the FBG.

  The optical pulse signal 21 transmitted through the transmission path 42 is incident on the decoder 62 via the second optical circulator 22 and decoded. The decoded optical pulse signal again enters the optical coupler 26 via the second optical circulator 22 and is demultiplexed into the optical pulse signal 27 and the optical pulse signal 29. The optical pulse signal 27 is restored as an electric pulse signal 36 by the photoelectric converter 28. That is, the binary digital electric pulse signal 15 which is information to be transmitted is restored and received as a binary digital electric pulse signal 36 by the receiving unit 40.

  A temperature sensor 64 is installed in the decoder 62, and the temperature of the FBG that constitutes the decoder is always measured, and the result is sent to the temperature controller 68 as a temperature signal 65. The wavelength control unit 32 calculates the temperature to be set in the FBG corresponding to the output 31 from the wavelength monitor 30. A control signal 67 is supplied to the temperature controller 68 so that the calculated temperature can be realized.

  The FBG constituting the encoder 60 and the FBG constituting the decoder 62 have the same effective refractive index periodic structure, and the periodic structures of the two are set to have an opposite relationship. That is, as will be described in detail later, if the FBGs constituting the encoder 60 and the FBGs constituting the decoder 62 are configured so that the unit FBGs are arranged in the order ABCDEFGHIKLMNOP as shown in FIG. Assuming that the input / output terminals of the FBG constituting the decoder 60 are on the side where the unit FBG indicated by A is arranged, the input / output terminals of the FBG constituting the decoder 62 are assigned the unit FBG indicated by P. Set to be on the side.

  The Bragg reflection wavelength of the FBG that constitutes the encoder or decoder (hereinafter sometimes referred to as “operating wavelength”) varies depending on the ambient temperature and other conditions. Here, it is assumed that a difference occurs between the effective refractive index periodic structures of the FBGs constituting the encoder 60 and the decoder 62 due to some cause such as ambient temperature, and the operating wavelength is changed. In this case, the effective refractive index periodic structure of the FBG constituting the effective refractive index periodic structure of the decoder 62 is made equal to the effective refractive index periodic structure of the FBG constituting the encoder 60 by adjusting the FBG temperature. There is a need.

  In addition, when installing the FBG in the encoder or decoder, it is actually difficult to install the encoder or decoder so that their operating wavelengths are the same.

  Therefore, the operation of at least one of the encoder and the FBG that constitutes the decoder is always kept the same as the operating wavelength of the FBG that constitutes the encoder on the transmission side and the FBG that constitutes the decoder on the reception side. It is necessary to adjust the wavelength from time to time.

  In transmission using the phase code method OCDM, if the operating wavelength of the FBG that constitutes the encoder on the transmitting side differs from the operating wavelength of the FBG that constitutes the decoder on the receiving side by several tens of pm or more, decoding is successful on the receiving side. Can not. That is, it is necessary to adjust as necessary so that the difference between the Bragg wavelengths of the FBGs constituting the transmitting-side encoder and the FBGs constituting the receiving-side decoder is less than several tens of pm.

  Thus, there is an FBG device that is devised so that the Bragg reflection wavelength of FBG is not easily affected by changes in the ambient temperature (see, for example, Patent Document 1). The apparatus described in Patent Document 1 has a configuration in which an optical fiber is attached to a negatively inflatable substrate and at least two separated portions on the surface of the substrate. An FBG is formed in the optical fiber. With reference to FIG. 3, the dependence of the operating wavelength on the change in the ambient temperature of the FBG device disclosed in Patent Document 1 will be described. The horizontal axis indicates the ambient temperature, and the vertical axis indicates the operating wavelength of the FBG device. When the FBG is not fixed to the negative expandable board, the straight line indicated by B indicates that the FBG is the negative expandable board. The case where it is fixed to and configured as an FBG device is shown.

When the ambient temperature changes from -40 ° C to + 125 ° C, if the FBG indicated by A is not fixed to the negative expansion substrate, the FBG operating wavelength is 1563.75 nm at -40 ° C. On the other hand, at + 125 ° C., it is 1556.65 nm, and the difference is 1.9 nm. On the other hand, when the FBG indicated by B is fixed to a negative expansion substrate and configured as an FBG device, the operating wavelength of the FBG fluctuates in the range of 1565.5 nm to 1565.7 nm, and the difference is 0.2 nm. It turns out that it is suppressed.
Special Table 2000-503415

  However, when the FBG device is used as an encoder and decoder in OCDM, if there is an operating wavelength variation of 0.2 nm depending on the ambient temperature environment, this is too large to be put to practical use. Further, in the apparatus disclosed in Patent Document 1, once the optical fiber having the FBG is fixed to the FBG apparatus, the operating wavelength cannot be changed to an arbitrary value based on an instruction from the outside. In optical communication by OCDM, when wavelength fluctuations of the light source that generates the optical pulse signal sent from the transmission side occur, it is necessary to change the operating wavelength according to this fluctuation. There is also a problem that cannot be done.

  Therefore, the present invention is characterized in that, for the purpose of solving the above-described problem, even if there is an environmental temperature fluctuation around the FBG device used as an encoder and a decoder, the operating wavelength hardly changes. To provide FBG equipment. In addition, when wavelength fluctuation of the light source that generates the optical pulse signal sent from the transmission side occurs, fine adjustment of about 100 pm with respect to the operating wavelength is performed only by temperature control based on an instruction from an external temperature controller. An object of the present invention is to provide an FBG device having a function capable of performing the above.

  In order to achieve the above object, a first FBG device of the present invention includes an FBG mounting base configured by sequentially stacking an FBG, a mounting plate, a base plate, and a temperature control plate, and an FBG set on the upper surface of the mounting plate. The contact portion includes a first fixing point and a second fixing point set with the FBG contact portion sandwiched between both ends of the mounting plate.

  Then, the FBG is fixed at the first fixed point and the second fixed point so as to contact the FBG contact portion. The lower surface of the mounting plate is in contact with the upper surface of the base plate in a slidable state, and the lower surface of the base plate is fixed in contact with the upper surface of the temperature control plate. Moreover, the temperature control board is comprised from the heat insulation member and the thermo module.

The mounting plate is preferably made of a material with a coefficient of thermal expansion of 1.2 × 10 ^-6 / K at the maximum, and the base plate is preferably made of a material with a thermal conductivity of 398 W / (m · K) at a minimum. It is. Specifically, it is preferable that the material constituting the mounting plate is Invar alloy and the material constituting the base plate is copper.

  Further, the second FBG device of the present invention includes an FBG, an FBG mounting base configured by laminating a guide plate and a temperature control plate, an FBG contact portion set on the upper surface of the guide plate, and both ends of the support base. And a first fixed point support and a second fixed point support connected via a connecting portion.

  The first fixed point and the second fixed point are provided at the tips of the first fixed point support and the second fixed point support, respectively, so that the FBG contacts the FBG contact portion. It is fixed at a fixed point. The temperature control plate is composed of a heat insulating member and a thermo module, and the lower surface of the guide plate is fixed in contact with the upper surface of the temperature control plate. The lower surface of the temperature control plate is fixed to a support base.

  The guide plate may be formed by stacking a mounting plate and a base plate, as in the first FBG device. In this case, the lower surface of the mounting plate is in contact with the upper surface of the base plate in a slidable state, the lower surface of the base plate is fixed in contact with the upper surface of the temperature control plate, and the lower surface of the temperature control plate is fixed to the support base. It is good to make it the structure fixed to.

  The first and second fixed point supports have a direction in which the first and second fixed points are displaced by the thermal expansion of the first and second fixed point supports, and a direction in which the support base is thermally expanded. It is good to fix to a support stand via a connection part in the parallel relationship.

Furthermore, the distance l ₁ from the end where the first fixing point support is fixed to the connecting portion to the first fixed point, from one end second solid fixing point support is fixed to the connecting portion to the second fixing point It is preferable that the distance l ₂ and the length L of the support base are set to have a relationship given by the equation (l ₁ β ₁ + l ₂ β ₂ ) = Lα. Here, α is a thermal expansion coefficient of the material constituting the support base, and β ₁ and β ₂ are thermal expansion coefficients of the material constituting the first and second fixed point supports, respectively.

  According to the first FBG device of the present invention, since the lower surface of the mounting plate is in contact with the upper surface of the base plate in a slidable state, expansion and contraction due to thermal expansion of the base plate is not transmitted to the mounting plate. That is, even if the base plate and the mounting plate are made of materials having different thermal expansion, the mounting plate is not distorted due to the thermal expansion of the base plate.

  In order to control the Bragg reflection wavelength of the FBG device by controlling the temperature of the FBG, heat transferred to the FBG after passing through the temperature control plate needs to be transmitted quickly. Therefore, the larger the thermal conductivity of the material constituting the base plate, the better. However, a material having a higher thermal conductivity tends to have a higher coefficient of thermal expansion. Therefore, the base plate is made of a material with high thermal conductivity so that the temperature change of the temperature control plate can be transmitted to the mounting plate as quickly as possible so that the influence of the thermal expansion of the base plate is not transmitted to the mounting plate. The lower surface and the upper surface of the base plate are in contact with each other in a slidable state.

  On the other hand, the mounting plate needs to have almost no thermal expansion even when the temperature changes. Since the first and second fixing points to which the FBG is fixed are provided at both ends of the mounting plate, when the mounting plate thermally expands, the distance between the first fixing point and the second fixing point increases, and the FBG This is because it grows.

Good by configuring the mounting plate with Invar alloy with a thermal expansion coefficient of 1.2 × 10 ^-6 / K at the maximum and the base plate with copper with a thermal conductivity of 398 W / (mK) at the minimum Results were obtained. Details of this point will be described later.

  Further, according to the second FBG device of the present invention, the first fixed point support and the second fixed point support connected to the both ends of the support base via the connecting portion are provided. A point and a second fixed point are provided at the tips of the first fixed point support and the second fixed point support, respectively. For this reason, the elongation due to the thermal expansion of the support base can be substantially offset by the elongation due to the thermal expansion of the first fixed point support and the second fixed point support. That is, when the ambient temperature of the second FBG device of the present invention changes, even if the support base, the first fixed point support, and the second fixed point support that fix the FBG are thermally expanded, the first The distance between the first fixed point and the second fixed point hardly changes, and as a result, the FBG hardly expands or contracts due to temperature fluctuation.

Here, if the first and second fixed point supports are thermally expanded, the direction in which the first and second fixed points are displaced and the direction in which the support base is thermally expanded are configured to be parallel, The offset effect due to the thermal expansion described above is the largest. As will be described in detail later, the distance l ₁ from one end fixed to the connecting portion of the first fixed point support to the first fixing point and the first end fixed to the connecting portion of the second fixed point support. 2 If the distance l ₂ to the fixed point and the length L of the support base are set to the relationship given by (l ₁ β ₁ + l ₂ β ₂ ) = Lα, the ambient temperature of the FBG device will fluctuate. However, the distance between the first fixed point and the second fixed point does not change. That is, even if the ambient temperature of the FBG device fluctuates, the FBG does not expand or contract, and the operating wavelength of the FBG constituting the FBG device does not fluctuate.

  As described above, according to the first or second FBG device of the present invention, when used as an encoder and a decoder, the FBG expands and contracts even when there is an environmental temperature fluctuation around the FBG device. It is possible to prevent fluctuations in the operating wavelength caused by this. As a result, the desired operating wavelength control for the FBG can be performed only by temperature control by the temperature control plate, and OCDM in which encoding and decoding can be performed with high accuracy is realized.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Each drawing shows a configuration example according to the present invention, and only schematically shows the cross-sectional shape and arrangement relationship of each component to the extent that the present invention can be understood. It is not limited. In the following description, specific materials and conditions may be used. However, these materials and conditions are only one of preferred examples, and are not limited to these. Moreover, in each figure, the same component is shown with the same number, and the overlapping description may be omitted. In addition, the drawings for explaining the structure of the FBG device give priority to the visibility of the drawings, and the geometrical overlap in the depth direction of the drawings has a strictness within a range in which the gist of the present invention is not misunderstood. There is a sacrificed part.

<First embodiment>
With reference to FIGS. 4A and 4B, the configuration of the first FBG apparatus of the present invention will be described. FIG. 4A is a schematic plan view of the first FBG device as viewed from above, and FIG. 4B is a schematic cross-sectional view as viewed from the side of the first FBG device.

  The first FBG device 100 includes an FBG mounting base 152 formed by stacking a mounting plate 110, a base plate 112, and a temperature control plate 150, an FBG contact portion 120 set on the upper surface of the mounting plate 110, and the mounting plate 110. A first fixing point 124 and a second fixing point 126 set with the FBG contact portion 120 sandwiched between both ends are provided.

  The FBG is formed on the optical fiber 132, and the FBG is fixed at the first fixed point 124 and the second fixed point 126 so as to contact the FBG contact portion 120. The temperature control plate 150 includes a heat insulating member 114 and a thermo module 116, and the lower surface 136 of the mounting plate 110 is in contact with the upper surface of the base plate 112 in a slidable state. Further, the lower surface 138 of the base plate 112 is fixed in contact with the upper surface of the temperature control plate 150.

  The base plate 112 is formed with a hole 134 for loading a temperature sensor. In the following description, the temperature sensor installed in the hole 134 for loading the temperature sensor may be referred to as the temperature sensor 134 as long as no misunderstanding occurs.

  In the first embodiment of the present invention, the FBG mounting base 152 is fixedly installed on the base bottom surface 154 of the FBG device casing 118. The FBG device casing 118 is configured to cover the FBG device base 118d with an FBG device casing cover 118u. A schematic plan view of the FBG device shown in FIG. 4 (A) as viewed from above is shown with the FBG device housing cover 118u removed. The reason for this structure is that the process of installing the FBG mounting base 152 and the like on the FBG device base 118d is considered in the process of manufacturing the first FBG device. The process of installing the FBG mounting base 152 or the like on the FBG device base 118d or fixing the FBG to the optical fiber 132 at the first fixing point 124 and the second fixing point 126 is performed by removing the FBG device housing cover 118u. This is because it can only be executed in the specified state.

  Both the FBG device base portion 118d and the FBG device housing cover 118u are made of a copper material whose surface is plated with gold. Of course, these constituent materials are not limited to copper, but may be aluminum, brass, or the like. The FBG device casing 118 of the first embodiment has a box shape, and a power supply terminal and a temperature sensor for the thermo module 116 are provided on either side of the optical fiber 132 in the longitudinal direction. An output terminal from 134 is provided (not shown). The first FBG device 100 is connected to the temperature controller 142 via this terminal. That is, a cable 156 for supplying power from the temperature controller 142 to the thermo module 116 and a cable 158 for outputting power from the temperature sensor 134 to the temperature controller 142 are provided on the side surface of the FBG device casing 118 described above. It is connected via a terminal.

  A glass epoxy material is used for the heat insulating member 114, but other materials having a low thermal conductivity such as a peak material and a mica material can also be used. In addition, the structure is not limited to the structure shown in FIG. 4 (B), and does not use the heat insulating member 114, and uses a screw or the like made of a material having low thermal conductivity instead of the base plate 112, and is configured to be bridged and fixed. It is good. In this case, since the location where the heat insulating member 114 exists becomes a space, a so-called air layer heat insulating structure is formed.

  The thermo module 116 is configured using a Peltier element. Therefore, overheating and cooling can be performed only by changing the direction of the current supplied to the Peltier element. FIG. 4 (B) shows a configuration example in which only one thermo module 116 is arranged, but it is also possible to install it at a plurality of locations in consideration of the dimensions of the FBG contact portion 120 and the like. Depending on this, the structure of the temperature controller 142 and the number of terminals to be provided on the side surface of the FBG device housing 118 may vary, but these belong to design matters only and define the technical scope of the present invention. It is not a content that should be taken into account.

By configuring the mounting plate 110 with an Invar alloy having a thermal expansion coefficient of 1.2 × 10 ⁻⁶ / K at the maximum, and configuring the base plate 112 with copper having a thermal conductivity of 398 W / (m · K) at a minimum. In the first FBG device 100, the allowable range of the environmental temperature change can be 24.6 ° C., and a favorable result is obtained that the range can be widened by 12.2 ° C. as compared with the conventional device. Details of this point will be described later.

  The material constituting the mounting plate 110 is not limited to Invar alloy, and a glass ceramic material or the like can be used. Further, the base plate 112 is not limited to copper, and aluminum or the like can be used. In any case, it is a matter of design which material is selected as long as it satisfies the above conditions of thermal expansion coefficient and thermal conductivity.

  Both the mounting plate 110 and the base plate 112 have a plate-like shape, and silicon grease is applied to the lower surface 136 of the mounting plate that is a boundary surface between them. As a result, the mounting plate 110 and the base plate 112 can slide relative to each other and maintain thermal contact. That is, if no silicone grease is applied, the thermal contact between the mounting plate 110 and the base plate 112 is incomplete, and the thermal conductivity at this boundary is small, but the silicon between the mounting plate 110 and the base plate 112 is not. Applying grease does not reduce the thermal conductivity during this period.

  A V-shaped groove (not shown) is provided on the upper surface 110u of the mounting plate 110 so that the FBG formation region of the optical fiber 132 contacts the upper surface 110u of the mounting plate 110 without impairing the thermal conductivity. Is formed so as to fit into the bottom of the V-shaped groove. The V-shaped groove is filled with silicon grease so that the thermal contact between the optical fiber 132 and the upper surface 110u of the mounting plate 110 is completely maintained via the silicon grease.

  In order to provide the first fixing point 124 and the second fixing point 126 at both end portions of the mounting plate 110, a first groove 128 and a second groove 130 are provided in a direction perpendicular to the V-shaped groove, respectively. The first and second grooves 128 and 130 prevent the fixing agent from diffusing over a wide range when the optical fiber 132 is fixed at the first fixing point 124 and the second fixing point 126, so that the fixing point portion of the optical fiber 132 is fixed. It is desirable to provide it so that it can be clearly defined.

  The optical fiber 132 is not pulled or slackened, and is bonded to the first fixing point 124 and the second fixing point 126 by an ultraviolet curable acrylic adhesive (catalog number VTC-2 manufactured by Summers Optical). It is fixed. Of course, not only this adhesive but also an epoxy adhesive may be used.

  As described above, the optical fiber 132 fixed to the first fixed point 124 and the second fixed point 126 of the FBG mounting base 152 passes through the through hole 122 provided in the FBG device casing 118 and is external to the FBG device casing 118. Pulled out. When the optical fiber 132 is passed through the through hole 122, the gap between the optical fiber 132 and the through hole 122 is filled with a sealing agent. This sealant is silicon gel. Even if the silicone gel is cured after a lapse of a predetermined time, the flexibility is not completely impaired, and the optical fiber 132 and the FBG device casing 118 are not completely firmly fixed. The role is to ensure airtightness.

  In order to make the lower surface 136 of the mounting plate 110 and the upper surface of the base plate 112 come into contact with each other in a slidable manner, and the mounting plate 110, the base plate 112, and the temperature control plate 150 are integrated to form an FBG mounting table 152. The mounting plate 110 and the temperature control plate 150 are fixed with fixing screws. Therefore, the base plate 112 is provided with a through hole through which a fixing screw for fixing the mounting plate 110 and the temperature control plate 150 is passed. The diameter of the through hole should be designed to be sufficiently larger than the outer diameter of the fixing screw. That is, even if the mounting plate 110 and the base plate 112 slide with each other due to the difference in thermal expansion coefficient, the base plate 112 expands or contracts due to the thermal expansion because there is a clearance for the gap between the through hole and the fixing screw. This is not transmitted to the mounting plate 110.

  The thermistor is used for the temperature sensor 134, but other than this, a thermocouple, a platinum thermal resistor, or the like can also be used. Further, in this embodiment, the temperature sensor 134 is loaded in the base plate 112 with a hole, but it can also be tightly fixed to the side surface or the like of the base plate. These matters all belong to the design matters.

  Next, the operation principle of the case where the FBG device according to the first embodiment of the present invention described above is used as an encoder or a decoder will be described. Since the FBG device according to the first embodiment can be used as both an encoder and a decoder, a case where the FBG device is used as a decoder will be described as an example here. Even when used as an encoder, the principle of controlling the temperature of the operating wavelength is the same.

  The wavelength monitor 146 (corresponding to 30 in FIG. 1) measures the degree of autocorrelation (the size of the eye opening) of the optical pulse signal 29 transmitted to the receiver 40, and the wavelength controller 144 (in FIG. 1). Corresponds to 32.) receives the output 131 from the wavelength monitor 146 and supplies a control signal 160 to the temperature control unit 148. An output 131 from the wavelength monitor 146 is an electrical signal reflecting the degree of autocorrelation (the size of the eye opening) of the optical pulse signal transmitted to the receiving unit 40. In the wavelength control unit 144, the relationship between the temperature measured by the temperature sensor 134 and the operating wavelength of the FBG is stored in the storage device indicated by M in the figure. Based on this stored information, the wavelength monitor 146 Based on the output 131 and the like, arithmetic processing such as calculating a control signal 160 to be sent to the temperature controller 142 is performed.

  In the temperature controller 142, a temperature control signal 156 is given to the thermo module 116 (corresponding to 66 in FIG. 1) based on the control signal 160 and the temperature-related signal 158 from the temperature sensor 134. In this way, the FBG contact portion 120 is heated or cooled via the base plate 112 by the thermo module 116 so that the temperature measured by the temperature sensor 134 is equal to the set temperature instructed from the temperature controller 142. .

  Here, the base plate 112 is heated or cooled by the thermo module 116, and the mounting plate 110 is heated or cooled via the lower surface 136 of the mounting plate 110 that is in thermal contact with the base plate 112. Since the base plate 112 and the mounting plate 110 are not mechanically firmly fixed, but are in contact with each other through silicon grease, the expansion and contraction of the base plate 112 caused by heating or cooling by the thermo module 116 is the mounting plate. 110 is not transmitted. Further, since the mounting plate 110 is made of a low thermal expansion coefficient material, the mounting plate 110 itself hardly expands or contracts. Since the FBG built in the optical fiber 132 is fixed to the first and second fixing points 124 and 126 set at both ends of the mounting plate 110, the optical fiber is changed along with the temperature change of the mounting plate 110. The temperature of the portion where 132 is in contact with the FBG contact portion 120 changes.

  When the ambient temperature surrounding the first FBG device 100 changes, the FBG device casing 118 expands and contracts as the environmental temperature changes, but the through hole 122 provided in the FBG device casing 118 and the light Due to the flexibility of the sealant filled in the gap with the fiber 132, the expansion / contraction of the FBG device casing 118 is absorbed by this sealant and is not transmitted to the optical fiber 132. As a result, no stress is applied to the optical fiber 132 in which the expansion and contraction of the FBG device housing 118 is fixed to the first and second fixing points 124 and 126, and the FBG built in the optical fiber 132 is not affected by the stress. The operating wavelength fluctuation caused by this does not occur.

  The FBG expands and contracts due to the stress, and the operating wavelength changes because the period of the periodic structure of the effective refractive index changes accordingly. On the other hand, the operating wavelength of the FBG changes even when the stress does not work and the temperature changes.

  It is known that the amount of change Δλ of the operating wavelength λ accompanying the temperature change is given by the following equation (1) (for example, see Andreas Othonos and Kyriacos Kalli: Fiber Bragg Gratings).

Δλ = λ ・ ΔT [(1 / Λ) (dΛ / dT) + (1 / n _eff ) (dn _eff / dT)] (1)
Here, ΔT is the amount of temperature change, Λ is the period of the periodic structure of the effective refractive index of the optical fiber, dΛ / dT is the thermal expansion coefficient of the optical fiber 132, and n _eff is the effective refractive index of the optical fiber. The fluctuation amount Δλ of the operating wavelength takes a positive value when the temperature rises, and the operating wavelength moves to the long wavelength side. On the other hand, if the temperature falls, the opposite is true.

For example, the operating wavelength λ is 1550 nm, the effective refractive index period Λ of FBG is 535.6 nm, the thermal expansion coefficient of optical fiber 132 is 5.5 × 10 ^-7 , the effective refractive index of FBG is 1.445, and the rate of change of the effective refractive index of FBG When (dn _eff / dT) is 8.6 × 10 ⁻⁶ and the ambient temperature is changed from 25 ° C to 45 ° C, the operating wavelength variation Δλ is 0.185 nm from the equation (1). λ is 1550.185 nm.

With reference to FIG. 5, the temperature control characteristics of the first FBG device of the present invention will be described. In FIG. 5, the horizontal axis represents the set temperature (° C) of the temperature controller, and the vertical axis represents the fluctuation amount Δλ (pm) of the operating wavelength, which is the Bragg reflection wavelength of the first FBG device. It is shown by. Approximating these observation values with a linear function, where x is the set temperature (° C) of the temperature controller and y is the amount of change in operating wavelength Δλ (pm),
y = 10.7x-266.7 (2)
Thus, it can be seen that the fluctuation amount Δλ (pm) of the operating wavelength per 1 ° C. set temperature of the temperature controller is 10.7 pm.

  Further, the operating wavelength can be adjusted in the range of 300 pm from 15 ° C. to 45 ° C., and can sufficiently cope with, for example, fluctuations in the wavelength of the light source that generates the carrier wave installed on the transmission side of the OCDM. Since the first FBG device employs a temperature controller that can set the temperature in units of 0.1 ° C., the minimum adjustment amount of the operating wavelength is 1 pm.

With reference to FIG. 6, the ambient temperature fluctuation dependency of the operating wavelength of the first FBG device of the present invention will be described. FIG. 6 shows the result of investigating the influence of the operating wavelength on the change in environmental temperature when the set temperature of the temperature controller of the first FBG device is 45 ° C. The horizontal axis represents the environmental temperature (° C.), the vertical axis represents the fluctuation amount Δλ (pm) of the operating wavelength, which is the Bragg reflection wavelength, of the first FBG device, and the measured value is indicated by ▲. Approximating these observation values with a linear function, where x is the set temperature (° C) of the temperature controller and y is the amount of change in operating wavelength Δλ (pm),
y = 0.61x-13.00 (3)
Thus, it can be seen that the fluctuation amount Δλ (pm) of the operating wavelength per 1 ° C. of the ambient temperature is 0.61 pm.

  The operating wavelength is from -20 ° C. to 60 ° C., and the variation rate of the operating wavelength Δλ is 0.61 pm. This value of 0.61 pm uses the first FBG device as an encoder or decoder. In some cases, the value is too large. However, since the wavelength fluctuation due to the environmental temperature is a long and slow fluctuation, it is in a range that can be sufficiently adjusted by the above-described temperature control by the wavelength controller via the temperature controller.

  As described above, according to the first FBG device, the wavelength can be changed to an arbitrary operating wavelength with an operating wavelength adjustment width of 200 pm or more, and this can be performed with an accuracy of 1 pm. It can be said that the FBG device has sufficient performance as an OCDM encoder or decoder.

<Second Embodiment>
With reference to FIGS. 7A and 7B, the configuration of the second FBG apparatus of the present invention will be described. FIG. 7A is a schematic plan view of the second FBG device as viewed from above, and FIG. 7B is a schematic cross-sectional view as viewed from the side of the second FBG device.

  The FBG device 200 includes an FBG mounting base 252 configured by laminating a guide plate 222 and a temperature control plate 250, an FBG contact portion 220 set on the upper surface of the mounting plate 210, a first fixing point 224, and a second fixing point. With 226.

  The guide plate 222 may be integrally formed, but in the second FBG device 200, the mounting plate 210 and the base plate 212 are laminated. In the second FBG device 200, as will be described later, the first fixed point 224 and the second fixed point 226 are provided not at both ends of the guide plate 222 but at a location different from the guide plate 222. Since the support 228 and the second fixed point support 230 are provided, the thermal expansion effect of the guide plate 222 is not transmitted to the optical fiber 132. Therefore, the guide plate 222 may be integrally formed. However, in this second FBG device, the heat of the guide plate 222 is somewhat due to the viscosity of the silicon grease via the FBG contact portion 220 and the optical fiber 132. In order to prevent the effect of expansion from being transmitted to the optical fiber 132, the mounting plate 210 and the base plate 212 are laminated as in the first 1FBG device.

  The feature of the second FBG device is that a first fixed point 224 and a second fixed point 226 are provided at the tips of the first fixed point support 228 and the second fixed point support 230, respectively. The first fixed point support 228 and the second fixed point support 230 are configured to be connected to both ends of the support base 260 via a connecting portion. In the second FBG device, the support base 260 is configured as the bottom surface of the FBG device base portion 218d, and the connecting portion is configured as a side surface of the FBG device base portion 218d. Hereinafter, within a range that does not cause confusion, a support base constituted by the bottom surface of the FBG device base portion 218d is referred to as a support base 260, and a connection portion constituted by the side surfaces of the FBG device base portion 218d is referred to as a connection portion 218d.

  Of course, the second FBG device is not limited to the above-described configuration, and the support base and the connecting portion are configured independently without using some components of the FBG device housing 218, and the support base is configured as the FBG device. It is good also as a structure fixed to the bottom face of the FBG apparatus base | substrate part 218d of the housing | casing 218. FIG.

  As shown in FIG. 7 (B), the first fixed point support 228 and the second fixed point support 230 are fixed in a direction perpendicular to the connecting portion 218d, and the connecting portion 218d is perpendicular to the support base 260. Fix in direction. As a result, the first fixed point support 228 is thermally expanded to displace the first fixed point 224 provided at the tip thereof (indicated by a vector Q) and the support base 260 is thermally expanded. (Indicated by the vector P and the vector P ′) can be fixed to the support base 260 via the connecting portion 218d in a relationship of being parallel to each other. In addition, the second fixed point support 230 is also thermally expanded, so that the second fixed point 226 provided at the tip thereof is displaced (indicated by a vector Q ′) and the support base 260 is thermally expanded. (Indicated by the vector P and the vector P ′) can be fixed to the support base 260 via the connecting portion 218d in a relationship of being parallel to each other.

  Considering the case where the environmental temperature of the second FBG is increased by adopting the above-described configuration, the vector P and the vector Q are opposite to each other, and the vector P ′ and the vector Q ′ are also opposite to each other. Since the direction is directed, the extension of the support base 260 is almost offset by the extension of the first fixed point support 228 and the second fixed point support 230, and the first fixed point 224 and the second fixed point The distance from the point 226 hardly changes. Further, when the environmental temperature of the second FBG falls, the above-described circumstances are the same except that the directions of the vectors P, P ′, Q, and Q ′ are reversed, and the first fixed point 224 and the first 2 The distance from the fixed point 226 hardly changes.

  In order to completely cancel out the elongation of the support base 260 described above by the extension of the first fixed point support body 228 and the second fixed point support body 230, the support base is made of materials and dimensions that satisfy the relationship described below. 260, the first fixed point support 228 and the second fixed point support 230 may be configured.

The distance from one end where the first fixed point support 228 is fixed to the connecting portion 218d to the first fixing point 224 is l ₁ , and the second fixed point support 230 is fixed from the one end where the second fixing point support 230 is fixed to the connecting portion 218d. The distance to 226 is l ₂ and the length of the support 260 is L. Further, the coefficient of thermal expansion of the material constituting the support base 260 is α, and the coefficient of thermal expansion of the material constituting the first and second fixed point supports 228 and 230 is β ₁ and β ₂ , respectively.

The sum of the magnitudes of the vector P and the vector P ′ is given by Lαt, where t is the amount of increase or decrease in the environmental temperature. On the other hand, since the magnitude of the vector Q is l ₁ β ₁ t and the magnitude of the vector Q ′ is l ₂ β ₂ t, the vector Q and the vector Q are given by assuming that the increase or decrease in the environmental temperature is t. The sum of 'is given by l ₁ β ₁ t + l ₂ β ₂ t.

  That is, when the increase or decrease amount of the environmental temperature is t, the change amount ΔL of the interval between the first fixed point 224 and the second fixed point 226 is given by the following equation (4).

ΔL = | Lαt- (l ₁ β ₁ t + l ₂ β ₂ t) | = | [Lα- (l ₁ β ₁ + l ₂ β ₂ )] t | (4)
ΔL does not depend on the increase or decrease amount t of the environmental temperature, that is, the interval between the first fixed point 224 and the second fixed point 226 is unchanged even if the environmental temperature increases or decreases.
Lα- (l ₁ β ₁ + l ₂ β ₂ ) = 0 (5)
In other words, it can be understood that the relationship given by (l ₁ β ₁ + l ₂ β ₂ ) = Lα may be set.

In the second FBG device, the first fixed point support 228 and the second fixed point support 230 are made of the same material and have the same length, that is, l ₁ = l ₂ = l and β ₁ = β ₂ = β is set so that Lα = (2l) β, that is, L / (2l) = β / α is approximately satisfied. Specifically, the support 260 is made of gold-plated copper and its length L is 70 mm. The first fixed point support 228 and the second fixed point support 230 are made of zinc and have a length l of 9.1 mm. Incidentally, according to "New Edition physical constants table" by Iida Ohno other ^{eds, α = 16.7 × 10 -6 /K,β=64.3×10} -6 / K, a since, L / (2l) = 70 / (2 × 9.1) = 3.846 and β / α = (64.3 × 10 ⁻⁶ ) / (16.7 × 10 ⁻⁶ ) = 3.850, and it can be seen that L / (2l) = β / α is almost satisfied.

  The FBG is formed in the optical fiber 132, and the FBG is fixed at the first fixed point 224 and the second fixed point 226 so as to contact the FBG contact portion 220. The temperature control plate 250 includes a heat insulating member 214 and a thermo module 216, and the lower surface 236 of the mounting plate 210 is in contact with the upper surface of the base plate 212 in a slidable state. Further, the lower surface 238 of the base plate 212 was fixed in contact with the upper surface of the temperature control plate 250. The base plate 212 has a hole 234 for loading a temperature sensor.

  In the second embodiment of the present invention, the FBG mounting base 252 is fixedly installed on the support base 260 which is the bottom surface of the base of the FBG apparatus casing 218. The FBG device casing 218 covers the FBG device base 218d with an FBG device casing cover 218u. A schematic plan view of the FBG device shown in FIG. 7A viewed from the top is shown with the FBG device housing cover 218u removed. This structure is the same as in the case of the first FBG device.

  In addition, since the material constituting the second FBG device, the configuration of the temperature control unit for controlling the operating wavelength, and the like are the same as those of the first FBG device, the description thereof is omitted.

With reference to FIG. 8, the temperature control characteristic of the second FBG device of the present invention will be described. In FIG. 8, the horizontal axis represents the set temperature (° C) of the temperature controller, and the vertical axis represents the amount of fluctuation Δλ (pm) of the operating wavelength, which is the Bragg reflection wavelength, of the second FBG device. It is shown by. Approximating these observation values with a linear function, where x is the set temperature (° C) of the temperature controller and y is the amount of change in operating wavelength Δλ (pm),
y = 10.7x-266.7 (6)
Thus, it can be seen that the fluctuation amount Δλ (pm) of the operating wavelength per 1 ° C. set temperature of the temperature controller is 10.7 pm.

  Further, the operating wavelength can be adjusted in the range of 300 pm from 15 ° C. to 45 ° C., and can sufficiently cope with, for example, fluctuations in the wavelength of the light source that generates the carrier wave installed on the transmission side of the OCDM. Since the first FBG device employs a temperature controller that can set the temperature in units of 0.1 ° C., the minimum adjustment amount of the operating wavelength is 1 pm.

With reference to FIG. 9, the ambient temperature fluctuation dependence of the operating wavelength of the second FBG device of the present invention will be described. FIG. 9 shows the result of investigating the influence of the operating wavelength on the change in environmental temperature when the set temperature of the temperature controller of the second FBG device is 45 ° C. The horizontal axis represents the ambient temperature (° C.), the vertical axis represents the amount of fluctuation Δλ (pm) of the operating wavelength, which is the Bragg reflection wavelength, of the second FBG device, and the measured values are indicated by ▲. Approximating these observation values with a linear function, where x is the set temperature (° C) of the temperature controller and y is the amount of change in operating wavelength Δλ (pm),
y = 0.0419x + 1.8199 (7)
Thus, it can be seen that the fluctuation amount Δλ (pm) of the operating wavelength per 1 ° C. of the ambient temperature is 0.0419 pm.

  The operating wavelength is from -20 ° C. to 60 ° C., and the variation rate of the operating wavelength Δλ is 0.0419 pm. This value of 0.0419 pm uses the second FBG device as an encoder or decoder. In this case, the value is sufficiently small as will be described later.

  As described above, according to the second FBG device, the wavelength can be changed to an arbitrary operating wavelength with an operating wavelength adjustment width of 200 pm or more, and this can be performed with an accuracy of 1 pm. It can be said that the FBG device has sufficient performance as an OCDM encoder or decoder.

<SSFBG>
The structure of SSFBG that constitutes this FBG device as FBG will be described in detail with reference to FIG. The SSFBG has a structure in which the SSFBG forming portion 8 is built in the optical fiber 6. FIG. 2 is a diagram schematically showing a configuration of an SSFBG for configuring an encoder or a decoder produced using a 15-bit M-sequence code string.

  In FIG. 2, the portion forming the SSFBG forming portion 8 is configured by arranging the constituent units indicated by A to P in series on one optical fiber. The structural units indicated by A to P are FBGs (units FBG) having all the same length and the same effective refractive index periodic structure (having the same Bragg reflection wavelength). That is, all the unit FBGs indicated by A to P have the same length and the same Bragg reflection wavelength. The Bragg reflection wavelength is set equal to the wavelength λ of the optical carrier wave (light constituting the optical pulse signal).

  The SSFBG forming unit 8 is configured by connecting a plurality of unit FBGs in series, but the adjacent unit FBGs are arranged in close contact with each other, or the adjacent unit FBGs are set to the phase π / 2 of the optical carrier wave. Arrange them at a corresponding interval. Here, the interval corresponding to the phase π / 2 is an interval corresponding to λ / 4, where λ is the wavelength of the optical carrier wave.

  Thus, the SBGG is an FBG configured to include a portion in which adjacent unit FBGs are arranged in close contact with each other and a portion in which adjacent unit FBGs are arranged with an interval corresponding to phase π / 2. . The content of the encoding is that at which positions the units FBG are arranged with an interval corresponding to the phase π / 2.

  If the unit FBGs are arranged without a gap, light having a Bragg reflection wavelength of the unit FBG is reflected. That is, the reflection spectrum has one maximum value λ, has a bell shape symmetrical to the maximum value, and the time waveform also becomes a pulse waveform having one maximum. On the other hand, if the intervals corresponding to the phase π / 2 are arranged at intervals between the adjacent unit FBGs, the time waveform of the reflected wave from such a structure SSFBG is the waveform having the above one maximum. It has a different and complex structure.

  Therefore, as shown in FIG. 2, the SFBBG is arranged by arranging a place where the adjacent unit FBGs are placed in close contact with each other and a place where an interval corresponding to the phase π / 2 is spaced according to a certain rule. If configured, the SSFBG becomes a reflector having unique reflection characteristics on the time axis corresponding to this rule.

  When a light pulse is incident on this reflector, it undergoes modulation resulting from the effective refractive index periodic structure of SSFBG having the inherent reflection characteristics corresponding to the above-mentioned rules. This modulation of the shape of the incident light pulse by SSFBG is called encoding. If an optical pulse signal obtained by modulating an optical pulse train with optical pulses arranged at equal intervals on the time axis with an electric pulse signal is incident on the SSFBG in the same manner as the optical pulse described above, the intrinsic reflection according to the rules described above is applied. It undergoes modulation due to the effective refractive index periodic structure of SSFBG with characteristics. That is, the optical pulse signal is encoded.

  The optical pulse signal encoded as described above is input to and output from the direction opposite to the direction that enters and exits the SSFBG into the SSFBG having the same effective refractive index periodic structure as when encoded. By doing so, the optical pulse signal before encoding is reproduced. That is, when encoding, if the optical pulse signal is encoded by entering and exiting from the side where the unit FBG indicated by A of SSFBG shown in FIG. 2 is arranged, the encoded optical pulse signal is Decoding can be performed by entering and exiting from the side where the unit FBG indicated by P of SSFBG shown in FIG. 2 is arranged.

  With reference to FIG. 10, the effect received by the decoded optical pulse signal when the operating wavelengths of the encoder and the decoder are shifted will be described. FIG. 10 shows the shape of the decoded optical pulse signal, where the horizontal axis is a time axis, and the vertical axis is the intensity of the optical pulse on an arbitrary scale. Here, in order to simplify the explanation, a simulated OCDM transmission experiment was performed using an optical pulse train in which optical pulses are regularly arranged at regular time intervals as an optical pulse signal. Accordingly, if the transmitted optical pulse signal is correctly decoded by the decoder of the receiving unit, an optical pulse train in which optical pulses are regularly arranged at a constant time interval is reproduced.

  In FIG. 10, this corresponds to the case where the optical pulse signal indicated by A is correctly decoded, and this shape is substantially the same as the optical pulse signal sent from the transmission unit. Here, three light pulses appear. On the other hand, the optical pulse signal indicated by B in FIG. 10 corresponds to the optical pulse signal when the transmitted optical pulse signal is not correctly decoded by the decoder of the receiving unit. Although the peak of the optical pulse signal indicated by B appears at the optical pulse signal peak position indicated by A, peaks also appear at other locations, and the same shape as the optical pulse signal sent from the transmitter No good transmission has been performed. In this case, the signal sent from the transmission unit may not be reproduced correctly.

  The reason why such a situation occurs is that the periodic structure of the effective refractive index of the SSFBG constituting each of the encoder and the decoder is not set equal due to the influence of the environmental temperature or the like. Incidentally, in the example in which the optical pulse signal indicated by B in FIG. 10 is observed, the difference in the operating wavelength of the FBG device between the encoder and the decoder is 15 pm.

  The apparatus disclosed in Patent Document 1, which is the prior art, varies by 0.2 nm with respect to an environmental temperature change of 165 ° C. from −40 ° C. to 125 ° C., that is, 1.21 pm per 1 ° C. On the other hand, according to the first FBG device of the present invention, when the environmental temperature changes by 1 ° C., it changes by 0.61 pm, and according to the second FBG device, it changes by 0.0419 pm.

  As described above, if the difference in operating wavelength of the FBG device between the encoder and the decoder is 15 pm, complete decoding cannot be performed, and the signal sent from the transmission unit may not be reproduced correctly. Thus, if the operating wavelength difference of the FBG device does not reach 15 pm between the encoder and the decoder, the following can be said as a condition that can be used as an OCDM encoder or decoder.

  The device disclosed in Patent Document 1, which is a conventional technology that changes 1.21 pm per 1 ° C of environmental temperature, is within the range of 12.4 ° C (15 ÷ 1.21 = 12.4) as the environmental temperature change. Since the difference in operating wavelength between the FBG device and the decoder does not reach 15 pm, it can be used without performing temperature control based on an instruction from an external temperature controller. On the other hand, according to the first FBG device, the range of change in environmental temperature is 24.6 ° C (15 ÷ 0.61 = 24.6), and according to the second FBG device, the range of change is 358 ° C (15 ÷ 0.0419 = 358). If so, it can be used similarly.

  According to the first FBG apparatus of the present invention, the permissible range of the environmental temperature change is 24.6 ° C., and since the conventional apparatus was 12.4 ° C., the range can be widened by 12.2 ° C. Moreover, according to the first FBG device of the present invention, since it has a function capable of fine adjustment of about 100 pm with respect to the operating wavelength only by temperature control based on an instruction from an external temperature controller, By using this temperature adjustment function, it can be used as an OCDM encoder or decoder. On the other hand, when the second FBG device of the present invention is used as an OCDM encoder or decoder, the allowable temperature change range is 358 ° C., so even if there is a change in environmental temperature, it is substantially based on it. It can be seen that no adjustment of the operating wavelength is required.

  From the above, it can be seen that the first and second FBG devices of the present invention are suitable for use as an OCDM encoder or decoder.

  As described in the first and second embodiments of the present invention, the first or second FBG device of the present invention hardly varies in the operating wavelength even when the ambient temperature varies. The operating wavelength can be changed to an arbitrary operating wavelength with an operating wavelength adjustment range of 200 pm or more, and the operating wavelength can be adjusted with an accuracy of 1 pm, which is suitable for use as an OCDM encoder or decoder. is there.

It is a block block diagram of an optical code division multiplexing transmission apparatus. FIG. 3 is a configuration diagram of an FBG fabricated using a 15-bit M-sequence code string. It is a figure which shows the temperature dependence of the Bragg reflection peak wavelength of the conventional FBG apparatus. It is a schematic block diagram of a 1st FBG apparatus. FIG. 6 is a diagram showing temperature control characteristics of the first FBG device. FIG. 6 is a diagram showing the ambient temperature dependence of the operating wavelength of the first FBG device. FIG. 3 is a schematic configuration diagram of a second FBG device. FIG. 6 is a diagram showing temperature control characteristics of a second FBG device. It is a figure which shows the environmental temperature dependence of the operating wavelength of a 2nd FBG apparatus. It is a figure where it uses for description of the effect by the shift | offset | difference of the operating wavelength of an encoder and a decoder.

Explanation of symbols

6: Optical fiber
8: SSFBG formation part
10: Transmitter
12: Optical pulse train generator
14: Modulation signal generator
16: Optical modulator
18: First optical circulator
22: Second optical circulator
62: Decoder
26: Optical coupler
28: Photoelectric converter
30, 146: Wavelength monitor
32, 144: Wavelength controller
40: Receiver
60: Encoder
62: Decoder
64: Temperature sensor
66, 116, 216: Thermo module
68, 142: Temperature controller
100: First FBG device
110, 210: Mounting plate
112, 212: Base plate
114, 214: Insulation member
118, 218: FBG device housing
120, 220: FBG contact area
122: Through hole
124, 224: First fixed point
126, 226: Second fixed point
128: 1st groove
130: Second groove
132: Optical fiber
134, 234: Hole for loading temperature sensor
148: Temperature controller
150, 250: Temperature control board
152, 252: FBG mount
200: Second FBG device
222: Guide plate
228: 1st fixed point support
230: Second fixed point support

Claims (8)

Fiber Bragg Grating (FBG)
An FBG mounting base configured by sequentially stacking a mounting plate, a base plate, and a temperature control plate;
FBG contact portion set on the mounting plate upper surface,
Comprising a first fixed point and a second fixed point set across the FBG contact portion on both ends of the mounting plate;
The FBG is fixed at the first fixed point and the second fixed point so as to contact the FBG contact portion,
The temperature control plate is composed of a heat insulating member and a thermo module,
The lower surface of the mounting plate is in contact with the upper surface of the base plate in a slidable state,
The lower surface of the base plate is fixed in contact with the upper surface of the temperature control plate ,
The mounting plate is made of a material having a thermal expansion coefficient of 1.2 × 10 ⁻⁶ / K at the maximum ,
The fiber bragg grating device , wherein the base plate is made of a material having a thermal conductivity of at least 398 W / (m · K) . The fiber Bragg grating device according to claim 1,
A fiber Bragg grating device characterized in that a material constituting the mounting plate is an Invar alloy. The fiber Bragg grating device according to claim 1,
A fiber Bragg grating device, wherein the material constituting the base plate is copper. Fiber Bragg Grating (FBG)
An FBG mounting base constructed by laminating a guide plate and a temperature control plate;
FBG contact portion set on the upper surface of the guide plate,
The first fixed point support and the second fixed point support connected to both ends of the support base via a connecting portion ,
The first fixing point is provided at a tip of said first fixed point support,
The second fixed point is provided at the distal end of the second fixing point support,
The FBG is fixed at the first fixing point and the second fixing point so as to contact the FBG contact portion,
The temperature control plate is composed of a heat insulating member and a thermo module,
The lower surface of the guide plate is fixed in contact with the upper surface of the temperature control plate,
A lower surface of the temperature control plate is fixed to the support ;
In the first fixed point support, the direction in which the first fixed point is displaced by the thermal expansion of the first fixed point support and the direction in which the support base is thermally expanded are parallel to each other. It is fixed to the support base via a connecting part,
In the second fixed point support, the direction in which the second fixed point is displaced due to thermal expansion of the second fixed point support is parallel to the direction in which the support base is thermally expanded. It is fixed to the support base via a connecting part,
A distance l ₁ from one end where the first fixed point support is fixed to the connecting portion to the first fixed point ;
A distance l ₂ from one end where the second fixed point support is fixed to the connecting portion to the second fixed point ;
The length L of the support base is
(l ₁ β ₁ + l ₂ β ₂ ) = Lα
A fiber Bragg grating device characterized by being set to a relationship given by:
Here, α is a thermal expansion coefficient of the material constituting the support base, and β ₁ and β ₂ are thermal expansion coefficients of the material constituting the first and second fixed point supports, respectively. The fiber Bragg grating device according to claim 4 ,
The guide plate is configured by laminating a mounting plate and a base plate,
The lower surface of the mounting plate is in contact with the upper surface of the base plate in a slidable state,
The fiber Bragg grating device, wherein a lower surface of the base plate is fixed in contact with an upper surface of the temperature control plate. The fiber Bragg grating device according to claim 4 ,
The mounting plate is made of a material having a thermal expansion coefficient of 1.2 × 10 ⁻⁶ / K at the maximum,
The fiber Bragg grating device, wherein the base plate is made of a material having a thermal conductivity of at least 398 W / (m · K). The fiber Bragg grating device according to claim 4 ,
A fiber Bragg grating device characterized in that a material constituting the mounting plate is an Invar alloy. The fiber Bragg grating device according to claim 4 ,
A fiber Bragg grating device, wherein the material constituting the base plate is copper.

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